Simulated directional gyro for aviation trainers



June 8, 1948.

G. LOWKRANTZ SIMULATED DIRECTIONAL GYRO FO R AVIATION TRAINERS :5 Sheets-Sheet 1 Filed July 28, 1943 GU| NE LOWKRANTZ INVENTOR.

ATTORNEYS.

June 8, 1948. e. LOWKRANTZ 4 3 SIMULATED DIRECTIONAL GYRO FOR AVIATION TRAINERS Filed July 28, 1945 5 sneaks-sheet 2 LOWKRANTZ IN V EN TOR Patented June 8, 1948 SIMULATED DIRECTIONAL GYRO FOR AVIATION TRAINERS Gunne Lowkrantz, Binghamton, N. Y., assignor to Link Aviation, Inc., Binghamton, N. Y., a corporation of New York Application July 28, 1943, Serial No. 496,460

Claims.

The present invention relates to instruments for use in grounded aviation trainers and is especially adapted to be used in trainers of the type described in United States Patents 1,825,462 and 2,099,857, but my invention may be used in other types of navigation trainers as well as for demonstration and other purposes.

It is a principal object of this invention to provide a simulated directional gyro for grounded aviation trainers.

It is another object of this invention to provide a simulated directional gyro which responds to movements of the trainer in simulation of the responses of a real directional gyro to movements of a plane in actual flight.

It is a further aim of this invention to provide a simulated directional gyro for a grounded aviation trainer which has means for simulating the precession of a real directional gyro.

Another object of this invention is to provide a simulated directional gyro for a grounded aviation trainer which has means for varying the rate of the simulated precession.

A further purpose of this invention is to provide a simulated directional gyro having means for setting the index means to any desired position.

Other objects and advantages of this invention will become apparent as the description proceeds,

reference now being made to the accompanying figures which show a preferred embodiment of my invention.

Fig. 1 is a general view of an aviation trainer of the type mentioned and showing the general relation thereto of the simulated gyro of this invention.

Fig. 2 is a perspective view of the outside of the instrument.

Fig. 3 is a rear view of the simulated directional gyro, certain parts being cut away and other parts being shown in cross section.

Fig. 4 is a general cross sectional and elevational view of the instrument, the right portion of Fig. 4 being a cross sectional view along the lines IV-IV of Fig. 3 and the left part of Fig. 4 being a cross sectional and elevational view along the lines IVaIVa of Fig. 3.

The directional gyros used in actual flight and before this invention in trainers of the type being mentioned comprise a mass universally mounted in neutral equilibrium with means for causing the mass to spin at a high rate of speed. The axis of rotation of the spinning mass remains in whatever direction it is set except for the slight precession caused by the friction of the bearings of the instrument, and, to a lesser extent, by the earths rotation. An azimuth scale is connected to the axis of the spinning mass and, consequently, it remains stationary except for the changes in its position caused by precession. The

outer case of the instrument being fixed to the instrument panel of the airplane of course assumes the direction of travel of the plane and, consequently, when the plane changes its direction as in turning the case moves about the azimuth scale and the other parts of the instrument connected to the rotating mass. A suitable index mark is provided upon the face of the instrument and as the plane turns, the movement of the instrument case and index mark with respect to the azimuth scale indicates the fact of change of direction and amount thereof.

The precession of the instrument due to the inherent friction also changes the relation of the rotating mass and azimuth scale to the index mark and indicates an apparent turn of the plane. This precession must be taken into account in actual flight and is done so by the pilot who resets the instrument every ten or fifteen minutes by reference to the magnetic compass. The following description will show that this invention provides means for simulating in a grounded aviation trainer the change in position of the azimuth scale relative to the index mark as a plane turns and also means whereby the precession of a real directional gyro may be simulated. Furthermore, means for resetting the instrument to any desired position will be described.

In Fig. 1 it will be seen that there is provided a fuselage I 0 in which is a seat for a student and controls simulating the regular controls of a real plane. This fuselage is mounted upon the universal joint designated by l2, the central support 14 being integral with the lower part of the universal joint. The lower portion of central support I4 is rotatably mounted in bearing housing l6 which is rigidly aflixed by means of bolts I 8 to the cross piece 20 which is afiixed to base 22. Also aflixed to the cross piece 20 is wheel 24 which has an annular groove 26. It should be borne in mind, therefore, that fuselage Iii, universal joint 12, and central support 14 are free to rotate with respect to bearing housing l6, cross piece 20, base 22 and wheel 24 which are stationary.

The trainer also comprises a turning motor 28 which is rigidly affixed by means of extending arms 30 to octagon 32 which is aflixed to trainer fuselage ill for rotation therewith. The output shaft 34 of turning motor 28 has rigidly aflixed thereupon wheel 36 which has an annular groove 38. Turning belt 40 is placed in the annular groove 38 and in the annular groove 26 of the wheel 24 which is fixed to the cross piece 20 of base 22. The output shaft 34 of turning motor 28 is rotated in response to the pressing of the rudder pedals within the trainer fuselage and inasmuch as turning belt 40' is firmly placed around wheels 24 and 3.6 by means of belt tightener 42 the friction between wheel 36 and belt is used as an index mark, is midway in the horizontal extension of window I44. It will be understood that a rotation of the trainer ID, as just described, causes a rotation of the casing I8 and index mark I54 around the stationary scale I36, and, therefore, changes the position of azimuth scale I36 relative to index mark I54, and when the position of azimuth scale 56 relative to index mark I54 is changed, the student in the trainer knows that the trainer is turning. In the event the trainer is turned to the left index mark I54 moves to the right, as seen in Fig. 1, thereby simulating the movement to the right of the index mark on the housing of a real gyro with respect to the azimuth scale when a plane in actual flight is turned to the left. In the event the trainer is turned to the right, index mark I54 is moved to the left in Fig. 4, thereby simulating the relative movements of the index mark and azimuth scale of the gyro in a plane in actual flight when the plane turns to the right. The student in the trainer of course, upon viewing the movements of scale I39 relative to the index mark I 54, receives the same intelligence that he would receive were he in actual flight when the same relative movements occur and he uses this information to pilot the trainer in the same manner that he would use it to fly a real plane. It should be noted that scale I36 is graduated so that a movement of the l,

trainer I9 to the right indicates a higher bearing, just as in the case of a real directional gyro in a plane.

It will be seen, therefore, that this invention provides a simulated directional gyro with means I for moving the azimuth scale relative to the instrument casing and index mark in response to a turning of the trainer in a manner simulating the relative movements of the azimuth scale and index mark of a real directional gyro in a plane in actual flight to a turning of the plane.

It has been implied that if a perfect directional gyro could be made it would maintain the direction of its axis of rotation in space undisturbed, except for the slight amount of precession in gyros of this kind caused by a rotation of the earth upon its axis. Since, however, it is impossible to completely eliminate friction in the instrument a frictional torque is present and causes an appreciable precession or creeping of the instrument. The precession in a real directional gyro produces the result that even though the plane be flying perfectly straight a slight movement of the azimuth scale with reference to the index mark of the instrument will occur. In

order that this error in the instrument shall not become excessive, about every minutes the instrument is checked with the magnetic compass in the plane and reset if necessary by means of the caging knob usually found under the azimuth scale. The following means have been incorporated in my invention to simulate the precession of a directional gyro and to enable the student in the trainer to reset the instrument periodically as he would do if he were in actual flight.

Reference is made to Figs. 3 and 4 which show precession motor I56 which rotates at the constant speed of four revolutions per minute. The output shaft of this motor is designated I56 and rigidly affixed upon this shaft is cam I66. As seen in Fig. 4, arm I62 is pivotally mounted upon horizontal shaft I 64 which extends longitudinally of the instrument casing. This shaft is mounted in oilite bearings I66 and I68 which are pressed in casting I19 which is held in place inside instrument housing I8 by means of screws I12. Upon the upper end of arm I62 is rotatably mounted a roller I14 which, as seen in Fig. 3, is mounted upon shaft I16 and held in place by means of spring clip I78. Below the shaft I'IE which holds roller H4 is another shaft I86 which is rigidly held by arm I62 and upon which is pivotally mounted a pawl I82 which is held upon shaft I66 by means of spring clip I34. There is a hole I86 in the left end of pawl I82 as seen in Fig. 3 and tension spring I88 is engaged therein. The other end of this spring is held by a hole 69 in casting I16 to which reference has been previously made. A cog wheel I62 is rigidly mounted upon the previously-mentioned shaft 394 by means of pin I 94 and upon the foremost end of shaft I64 as seen in Fig. 4 is rigidly affixed by means of pin I96 a worm I98 which drives worm gear 206 which has an integral upstanding portion 292, the inner upper end of which is geared for cooperation with idler gears. 98 and I66 which have been previously described. Gear 296 is free to rotate upon central vertical shaft 92. A positioning collar 20I is held upon shaft I64 by means of set screw 263.

Whenever motor I56 is energized the output shaft I58 rotates as does cam I69 which is rigidly afiixed thereupon. When cam I69 reaches such a position that roller I'M is in the depression 264 of cam I60 spring I86 pulls pawl I82 and arm I62 to its leftmost position as seen in Fig. 3 and pawl I82 engages one of the teeth of cog wheel I92. A spring stop I93 held by casting I10 and screw I prevents a counterclockwise turning of co wheel I92 when pawl I82 is pulled to the left in Fig. 3. As the rotation .of cam 466 continues the eccentric nature of the cam pushes roller I14 to the right and by means of shaft I76 upon which this roller is mounted the upper end of arm I62 moves in that direction. Pawl I32 being engaged with cog wheel I92 rotates this cog wheel clock- Wise as seen in Fig. 3 and shaft I64 upon which this cog wheel is rigidly mounted is turned in the same direction. Worm I98 is therefore turned, turning worm gear 296 and its upstanding integral portion 292, the upper inner side of Which, it will be recalled, is geared for cooperation with idler gears 68 and I66. The rotation of internal gear 262, through the medium of gears 98 and I68 and shafts I62 and H9, will rotate inner clutch member I64 around gear 96 which is integral with central shaft 92 because gear 76 which is rigidly aflixed to upstanding shaft 92 is held in place by the drive through flexible shafting 62 to the heading take-off at the base of the trainer. The rotation of inner clutch member I 94 caused by a rotation of member 262 will rotate outer clutch member H8 in the event that the clutch is engaged and a rotation of hub I26, flange I26 and azimuth scale I 35 will result. The position of azimuth scale I36 relative to index mark I54 will therefore change in exact simulation of the changing of the relative positions of the azimuth scale and index mark of a real directional gyro as a result of the precession of the instrument.

It will be appreciated, therefore, that my invention provides means for simulating the precession of a real directional gyro.

The rates of precession of directional gyros vary from instrument to instrument and as far as a given directional gyro is concerned, the older the instrument becomes the greater its precession usually becomes. The following mean have been ferent rates of precession'in real directional gyros maybe-simulated;

Itwill be seen in Fig.3. that 'there is attached to the bottom of the instrument housing bymeans of screws2 0.65anrarm208 which has two'upstanding limit piecesa2I 0. A precession adjusting screw 2 I 2 is held by casting-4.10 which-is suitably. tapped for the reception thereof; Integral'with screw 2 I 2- pawl I82 and theuppen end of arm IE2 to theleft in Fig, 3, paw-1482 and the upperend of arm- I62 will-notbe able to travel as-iar to the left as though-precessionadjusting screw-212 were not in its innermost position; It-will therefore be realizedthat by positioning I precession adjusting screw 2 I2, the'amountof rotation of cog wheel I92 for-each revolution of precession motor 156 may be regulated and, therefore; theamount 'of' precessionas. shown bythe position ofazimuth scale I 36 may be varied.

It will'therefore'be realized'thatmy. invention also provides means for varying the rate of simulated precession, thereby making it possible to simulate the precession in difierent instruments.

It should be noticed that the turning of the trainerrotates gear 96=onshaft 92, and this gear by-meansof-idlergears S8 and I rotates inner clutch member-104:.- The output'of precession mQtOrIEE- at the: samertimeis applied to idlergears 98 and Hill-by means of internal gear'mem-- ber 202which in turn notatesinnen clutchmenh ber I04.

I Mand therefore of-azimuthscale I36 is the differentialresult of the turning of the trainer and the simulatedprecession; just as inactual flight-- the movement/of the azimuthscale relative to the index markis the differential result'ofthe turning' of the planeand-precession of the-instrument; As previously explained, in actual flight the directional gyro mustbe-periodically checked with the :magnetic' compass and reset if=necessary by means of the cagingknob usually positionedrunderneath-the azimuth: scale. The following means have been provided in my invention in order that this practice maybe simulated.

As seen in Fig.4, a-simulated caging knob 2H5- is affixed by meansvot set screw 2 I 8 upon sleeve 220 which is mounted upon horizontal shaft 222.

Theright end of shaft 222-is threaded into'the right end of sleeve 220-:an'd.locknut 224 is positioned-upon the-outer rig-htendof shaft 222.. A

bevel gear'226 -is rigidly afiixed-on'the'leftend of shaft 222 for "rotation therewith. An'oilite bearing 2201's pressed into a-bore in the front-face of casting 'I8-and this bearing has two holes drilled-- therein 180 apart-for positioning balls-230i"- A groove 232 is formed arcundrsleeve 220r-andthese balls ridein this groove-under thecompression of springs 234. A screw -235"holdsthe lower spring 234 in place.

Fig.4 shows caging knob. 2I6 in its. innermost. position which isthe positionthat.-.it.occupies. when it is desiredito changethe setting of.azi-- muth. scale I36... Wh'enin this position,=,itwil1. berseen that.,bevel gear.22l engages the..bevel The rotation of inner clutch member gear formed integrally'with the lower surface. of outer clutchmember IIdandthatouterclutch member -I I8; central hub I20,- flange I2? and azimuth scale-I3B are pushed upward; 'thereby disengaging the clutch: members I 04 and :I I8.--- A- rotation of knob 2 I 6 I will then rotate bevel: gear I 226, outer clutchmember H8, central hub I20 and azimuth scale I36: After azimuth scale I36 has beenset'to the proper position by reference to the magnetic compass in the trainer;

knob-2H5 is pulled'outward-from the instrument.

housing, bevel gear 226 becomes disengaged'from' the bevel gear formed integrally with outer clutch member H8 and gravity pulls-central. hub I 20, azimuth scale I30 and outer clutch member H8 downward'so'that the twoclutch members I04 and I I0 are engaged.

It will be seen,- therefore, that my invention provides a simulated directional gyro-thavingsan azimuth scale and an index rnarkin exactsimu-- lation of the azimuth scale'and index mark-of a real gyro and that the-relative'movements -of the azimuthscale and-indexmark in areal-gyroin a plane in actual flight caused by the turning .of the plane may-be simulated by-my invention which provides means for changing the relative positions of the azimuth-scale and index arm of the simulated gyro in response to theturningofi the trainer. vides-means for simulating the precession of a real gyro and means-are provided whereby different ratesof precession may be introduced,

thereby simulating the various rates of precessions indifferent directional I gyros. My invention also-provides means whereby the azimuth.

scale of: the. simulated. gyro maybesetto any desired position.

The foregoing being but a preferred embodiment of myinvention in which numerous changes maybe made without departing from=the sub" stance, I limitv myself-only by thefollowing claims;-

Iclaim:

1. In a grounded aviation trainer comprising a fuselage having a place for a student pilot and'a pair of rudderpedals,-a directional gyrosimulator' comprising an indexscale; means connecting' saidindexscale with a member mov-- able in response to themovements of said rudder .pedals. for. positioning said index scale in re sponseto the movements-of said rudder pedals,

and-additionahmeans for'positioning said -in-' dex scale in a predetermined manner simultaneously with the positioning thereof in response to the movement of said rudder pedals.-

2. Ina grounded. aviation trainer comprising a fuselage having a place for a student pilot and a pair of rudder pedals, a directional'gyro simulator-comprising an'index scale, means con necting' said index scale with a member mov-- able in'response to the movements of said rudder pedals for-positioningsaid index scale in: rc-' spouse to the movements of said rudder :pedals in simulation of theapparent movement ofltheindex means of a directionalgyro in' a-plane in actual flight in response to the turning-nor the plane, and a secondmcans difierentially; connected vwithsaid first means for positioningisaid index scale. ina predeterminedmanner in..simulation of the movement of the index means of a directional gyro ina plane in actual flight as a result of the precessionof the instrument.

3. In a groundedaviation trainercomprisinga I fuselage having a place for a student pilot and .a pairof rudder pedalaaqirectional gyro simu- Furthermore, this inventionrlpro later comprising an index scale, means connecting said index scale with a member movable in response to the movements of said rudder pedals for moving said index scale in response to the movements of said rudder pedals, a second means comprising a source of power for moving said index scale, said second means being operable independently of the movements of said rudder pedals, means for disconnecting said first two driving means, and a third means for manually positioning said index scale when said first two means are disconnected.

4. In a grounded aviation trainer comprising a fuselage rotatably mounted upon a stationary base, a directional gyro simulator comprising an index scale carried in said fuselage, take-oil means operated by the rotation of said fuselage with respect to said stationary base arranged to prevent a rotation of said scale as a result of the rotation of said fuselage, and means independent of the rotation of said fuselage for moving said scale in simulation of the movement of the scale of a real directional gyro in a plane in actual flight as a result of the precession of the instrument.

5. In a grounded aviation trainer comprising a fuselage rotatably mounted upon a stationary base, a directional gyro simulator comprising an index scale carried in said fuselage, take-oil means operated by the rotation of said fuselage with respect to said stationary base arranged to prevent a rotation of said scale as a result of the rotation of said fuselage, means for moving said scale in simulation of the movement of the scale of a real directional gyro in a plane in actual flight as a result of the precession of the instrument, and means for manually positioning said scale.

6. In a grounded aviation trainer comprising a fuselage rotatably mounted upon a stationary base, a directional gyro simulator comprising an index scale carried in said fuselage, take-off means operated by the rotation of said fuselage with respect to said stationary base arranged to prevent a rotation of said scale as a result of the rotation of said fuselage, and means differentially arranged with said take-01f means for moving said scale in simulation of the movement of the scale of a real directional gyro in a plane in actual flight as a result of the precession of the instrument.

7. A directional gyro simulator for instruction in the art of navigation comprising, in combination, a casing; a scale graduated like the scale of a real directional gyro mounted in said casing for relative movement with respect to said casing; a first driving means comprisin a direct mechanical connection coupled to said graduated scale and to a movable member located outside said casing for controlling the relative movement between said scale and said casing; and a second driving means comprising a direct mechanical connection coupled to said graduated scale for causing a movement of said index means relative to said casing, to simulate the movement of the index means of a real gyro relative to its casing as a result of precession.

8. A directional gyro simulator for instruction in the art of navigation comprising, in combination, a casing; a scale graduated like the scale of a real directional gyro mounted in said casing for relative movement with respect to said casing; a first driving means comprising a direct mechanical connection coupled to said graduated scale and to a movable member located outside said casing for controlling the relative movement between said scale and said casing; a second driving means comprising a direct mechanical connection coupled to said graduated scale for causing a movement of said index means relative to said casing, to simulate the movement of the index means of a real gyro relative to its casing as a result of precession; and a manually operable member arranged to selectively disconnect said two-mentioned driving means from said scale, whereupon said scale may be manually rotated relative to said casing.

9. A directional gyro simulator for instruction in the art of navigation comprising, in combination, a casing; a scale graduated like the scale of a real directional gyro mounted in said casing for relative movement with respect to said casing; a first driving means comprising a direct mechanical connection coupled to said graduated scale and to a movable member located outside said casing for controlling the relative movement between said scale and said casing; a second driving means comprising a motor mechanically connected directly to said scale for moving said scale relative to said casing, to simulate the movement of the index means of a real gyro; and means for selectively adjusting the rate of movement of said index scale caused by said second driving means.

10. A directional gyro simulator for instruction in the art of navigation comprising, in combination, a casing; a scale graduated like the scale of a real directional gyro mounted in said I casing for relative movement with respect to said casing; a first driving means for said scale comprising a difierential and a clutch, said clutch being directly coupled to said scale; a second driving means comprising a motor and ratchet and pawl means, said motor being connected to said ratchet and pawl means and said ratchet and pawl means being connected through said differential and clutch to said index scale; manually operable means for adjusting said ratchet and pawl means; and a manually operable memher for selectively disengaging said clutch from said' index scale and moving said index scale relative to said casing.

GUNNE LOWKRANTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,576,824 Heath Mar. 16, 1926 1,589,174 Heath June 15, 1926 1,617,310 Sperry Feb. 8, 1927 1,701,582 Mengden Feb. 12, 1929 1,825,462 Link Sept. 29, 1931 2,069,285 Stark Feb. 2, 1937 2,093,417 Carter Sept. 21, 1937 2,095,716 Ribero-lles Oct. 12, 1937 2,099,705 Reichel Nov. 23, 1937 2,099,857 Link Nov, 23, 1937 2,110,869 Crane Mar. 15, 1938 2,226,726 Kramar Dec. 31, 1940 2,249,373 Alkan July 15, 1941 2,283,190 Crane May 19, 1942 2,326,764 Crane Aug. 17, 1942 2,336,436 Biendorf Dec. 8, 1943 2,352,101 Hutter June 20, 1944 2,401,029 Thompson May 28, 1946 

